Leishmaniasis refers to a group of diseases that afflicts 12 million persons worldwide, with an estimated 2 million new infections occurring annually (1). All three forms of the disease, visceral, cutaneous and mucosal leishmaniasis, are prevalent in our study areas in the Northeast of Brazil. The main objective of this program is to strengthen and expand knowledge of the host-parasite relationship in leishmaniasis that will allow new forms of therapy and control of leishmaniasis. The Federal University of Bahia (UFBA) Tropical Medicine Research Center was established in 1991. The Federal University of Rio Grande do Norte (UFRN) joined the TMRC in 1996 to share their expertise in leishmaniasis. Strong collaborative programs have been established between Brazilian and US investigators in tropical diseases. This proposal will emphasize the application of molecular approaches to determine host (immunologic, genetic) and parasite (genetic, phenotypic) factors contributing to the pathogenesis of tegumentary and visceral leishmaniasis. New diagnostic and therapeutic approaches are the ultimate goals of this research. An increased understanding of the pathogenesis and genetics of leishmaniasis may provide the basis for innovative clinical strategies. The program has two cores (administrative, data management) and 3 scientific projects. Project I, "The role of Leishmania braziliensis strain polymorphism on disease outcome and distribution" will determine the role of parasite polymorphisms in the different clinical forms associated to L. braziliensis infection and identify markers for the molecular diagnosis of leishmaniasis. Project II, "Protective and Pathogenic Immune Responses in Tegumentary Leishmaniasis" will identify at molecular and cellular level immunological responses associated with protection and those responses associated with pathology in individuals with subclinical L. braziliensis infection and in patients with cutaneous and mucosal leishmaniasis. The duration of immunologic memory to soluble leishmania antigens and recombinant vaccine candidates antigens will also be evaluated in individuals with a past history of L. braziliensis or L. chagasi infection. Project III, "Genetic Determinants of Leishmaniasis" will expand our knowledge of genes associated with the clinical expression of L. chagasi and L. braziliensis infection. Studies performed in theses projects will seek to identify new interventions to control and/or ameliorate leishmaniasis worldwide. PROJECT 1: "The role of Leishmania braziliensis strain polymorphism on disease outcome and distribution" (Schriefer, A.) PROJECT 1 DESCRIPTION (provided by applicant): We recently found that distinct clades of Leishmania braziliensis genotypes are associated with different forms of leishmaniasis [i.e. localized cutaneous (CL), disseminated (DL) and mucosal (ML) leishmaniases], and lead to differential distributions of these diseases in endemic regions. Our long term goals are: (1) determine whether the geographic distribution of L. braziliensis clades, and their dynamic changes in the endemic region over time, will correlate with the geographical pattern of human disease manifestations;and (2) develop a better understanding of how the human infection with the different strains of L. braziliensis results in the different outcomes of leishmaniasis. The specific aims of the current application are: (1) use randomly amplified polymorphic DNA (RAPD) and multilocus sequence typing (MLST) to genotype Leishmania braziliensis causing CL, ML and DL in the endemic region of Corte de Pedra / Brazil;(2) evaluate the spatial and temporal distributions of CL, ML and DL in Corte de Pedra;and (3) compare the effects of human peripheral blood mononuclear cells (PBMC) infection with CL, ML or DL clades of L. braziliensis on global gene expression in host cells. In the first aim we will isolate and culture parasites from CL, ML and DL cases.genotype them by RAPD and MLST, classify the genotypes by relatedness, and check clades of genotypes are associated with CL, ML or DL. In the second aim we will obtain the geographical coordinates of the living sites of the patients that participated in aim one by GPS, then compare their distributions in the study area using Arclnfo geographical information software and geostatistics. In the third aim PBMC samples of healthy donors will be infected with L. braziliensis isolates associated with CL, ML or DL in vitro, then total RNA will be collected at different time points and the expression of immune and nonimmune related genes will be assessed by micro array, using specific software packages. The leishmaniases cause a major public health burden with 400 million individuals at risk in tropical and subtropical areas of the globe. L. braziliensis derived CL, ML and DL present diverse responses to the first line drugs, as well as prognosis. The better understanding of the relationship between parasite strain and disease forms, and of the effects of parasite strains on host cells that lead to the diverse outcomes may lead to improved therapeutics / prophylaxis, and better case management, with important impact on this disease burden.